Last summer I marked the locations of over 250 nylon hedgehog cactus plants (Echinocereus viridiflorus). I planned to start a study of some kind on these plants. As time passed, I removed many of these flags and replaced them with roof nails with bright orange plastic collars. I could push these into the soil and the plastic collar was flush with the ground. Easy to mow around, when necessary for weed control, and would not hurt if one of our horses stepped on it.
As noted in my previous post http://nancyrileynovelist.com/?p=116, rabbits have taken a toll on these marked plants. In several spots, I found a depression where the plant had been – just the marker left to show a cactus had been there. Just a random observation of 12 markers showed only two plants remaining.
When I was surveying for the Colorado hookless cactus (Sclerocactus glaucus), botantists from the Bureau of Land Management told me that around 2008-2009 many individual cactus disappeared, probably eaten by rabbits. Most of the plants they were finding in current surveys were no more than approximately five years old. This is important information when working with a federally listed (Endangered Species Act) species. The goal with every listed species is to recover it to the point that it can be removed from the list. If rabbits are decimating a local cactus population, it would be beneficial to know methods to protect plants, deter rabbits, and propagate more cactus.
Later this spring, when the cacti are most visible, I will conduct a survey of my marked plants and estimate the amount of rabbit herbivory or predation. This will give me a starting point for studies on my property.
I have not been able to get close enough to video rabbits eating these cactus. The largest nylon hedgehog cactus on my property are about 1.5 inches in diameter and around 2 inches tall. Below is a video I found on YouTube video of a rabbit happily munching a much larger cactus to illustrate my point of how much damage one rabbit can inflict.